KR101895365B1 - Lithium ion secondary battery - Google Patents

Abstract

The power storage device is provided with a current interruption device. The current blocking device includes a first energizing member, a second energizing member, a deforming member, and a first sealing member. The first energizing member is fixed to the case. The second energizing member is disposed at a position facing the first energizing member. The end of the deformable member is fixed to the first energizing member. And the central portion of the deformable member is fixed to the second energizing member. The first sealing member is disposed between the first energizing member and the second energizing member. The second sealing member is disposed between the enlarged portion of the first energizing member and the case. The material of the second seal member is rubber. The second seal member airtightly holds the inside of the case from the outside of the case.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a lithium ion secondary battery,

This application claims priority based on Japanese Patent Application No. 2014-089298, filed on April 23, 2014. The entire contents of which are incorporated by reference in this specification. This specification discloses a technique relating to a power storage device having a current interruption device.

Development of a current interrupting device for interrupting the current flowing between the electrode terminals (the positive electrode terminal and the negative electrode terminal) when the electrical storage device is overcharged or when a short circuit occurs in the electrical storage device is under development. The current interrupting device is disposed between the electrode terminal and the electrode (between the positive electrode terminal and the positive electrode or between the negative electrode terminal and the negative electrode). The current interruption device interrupts the conduction between the electrode terminal and the electrode when the pressure in the case of the power storage device rises. The current interrupting device of Japanese Laid-Open Patent Publication No. 2012-28008 has a second energizing member opposed to the first energizing member. The second energizing member is connected to the electrode. Further, a deformable member is disposed between the first energizing member and the second energizing member. The end portion of the deformable member is connected to the first energizing member and the center portion is connected to the second energizing member. In Japanese Laid-Open Patent Publication No. 2012-28008, a sealing member is disposed between the case and the first energizing member. Hereinafter, Japanese Laid-Open Patent Publication No. 2012-28008 is referred to as Patent Document 1.

Japanese Laid-Open Patent Publication No. 2012-28008

In Patent Document 1, the sealing member is disposed between the case and the first energizing member to keep the inside of the case airtight from the outside of the case. However, if the space between the case and the first energizing member is completely sealed, the pressure in the case may gradually rise due to the gas generated when the power storage device is normally operating. As a result, although the power storage device does not cause an abnormality, the current cutoff device may operate to interrupt the conduction between the electrode terminal and the electrode. That is, the sensitivity of the current interrupting device is reduced. The present specification provides a technique for suppressing the deterioration of the sensitivity of the current interruption device.

The power storage device disclosed in this specification has a case, an electrode, an electrode terminal, and a current interrupting device. The electrode is housed in the case. The electrode terminal is fixed to the case and exchanges electricity with the electrode. The current cutoff device interrupts the conduction between the electrode and the electrode terminal when the pressure in the case exceeds a predetermined value. The current interrupting device includes a first energizing member, a second energizing member, a deforming member, and a first sealing member. The first energizing member is fixed to the case. The first energizing member is connected to the electrode terminal. The second energizing member is disposed at a position facing the first energizing member with an interval from the first energizing member. And the second energizing member is connected to the electrode. The deformable member is disposed between the first energizing member and the second energizing member. An end of the deforming member is connected to the first energizing member, and a central portion of the deforming member is connected to the second energizing member. The deformable member is non-conductive with the second energizing member when the pressure in the case exceeds a predetermined value. The first sealing member is disposed between the first energizing member and the second energizing member. The first seal member hermetically holds the inside of the current interruption device from the outside of the current interruption device. The power storage device disclosed in this specification further includes a second seal member. The second sealing member is disposed between the case and the first energizing member. The second seal member airtightly holds the inside of the case from the outside of the case. The material of the second seal member is rubber.

In the above-described electric storage device, the inside of the case is kept airtight from the outside of the case by the second seal member. The material of the second seal member is rubber. The rubber has gas permeability. Therefore, when gas is generated in the case, the gas gradually permeates through the second seal member before the pressure in the case excessively rises, so that the pressure in the case can be appropriately maintained. As a result, a malfunction of the current interruption device is suppressed. Further, when an abnormality occurs in the power storage device, the pressure in the case rises rapidly. Therefore, before the gas passes through the second seal member, the pressure in the case exceeds a predetermined value, and the current interruption device operates to interrupt the conduction between the electrode terminal and the electrode.

According to the technique disclosed in this specification, it is possible to suppress the deterioration of the sensitivity of the current interruption device.

1 is a cross-sectional view of an electrical storage device according to the first embodiment.
2 is an enlarged cross-sectional view of a current interrupter used in the power storage device of the first embodiment.
3 is a sectional view of the power storage device of the second embodiment.
4 is an enlarged cross-sectional view of a current interrupter used in the power storage device according to the second embodiment.

(Mode for carrying out the invention)

Hereinafter, some technical features of the electrical storage device disclosed in this specification will be described. In addition, each of the following items has a technical usefulness alone.

The power storage device includes a case, an electrode assembly, an electrode terminal, and a current cutoff device. The electrode assembly is accommodated in the case and may have a positive electrode and a negative electrode. The electrode terminal may pass through the inside and outside of the case. That is, a part of the electrode terminal may be located outside the case, and another part of the electrode terminal may be located inside the case. Further, the electrode terminal may be fixed to the case. The electrode terminal may receive electricity from the electrode (positive electrode or negative electrode). The current blocking device may be connected to the negative electrode terminal and the negative electrode. In this case, the current interruption device is disposed on the current path between the negative terminal and the negative electrode, and switches the negative terminal and the negative electrode from the conduction state to the non-conduction state when the breakdown voltage of the case exceeds a predetermined value. The current blocking device may be connected to the positive electrode terminal and the positive electrode. In this case, the current interruption device is disposed on the current path between the positive electrode terminal and the positive electrode, and switches the positive electrode terminal and the positive electrode from the conduction state to the non-conduction state when the breakdown voltage of the case exceeds a predetermined value.

The current interrupting device may include a first energizing member, a second energizing member, a deforming member, and a first sealing member. The first energizing member may be fixed to the case of the power storage device. The first energizing member may be connected to the electrode terminal. Alternatively, the first energizing member may be part of the electrode terminal. The first energizing member may include a protruding portion protruding outside the case through a through-hole formed in the case and a large-diameter portion located in the case. Further, a bolt portion may be formed on the projecting portion. The first energizing member may be fixed to the case by fastening a nut to the bolt portion formed in the protruding portion. The size of the enlarged diameter portion may be larger than the through hole formed in the case. That is, a part of the enlarged diameter portion may be opposed to the case. The end face of the first energizing member on the electrode assembly side may be opposed to the second energizing member. A depressed portion may be formed at the central portion of the cross section so as to be punched out on the side opposite to the second energizing member.

The second energizing member may be disposed at a position facing the first energizing member with an interval from the first energizing member. The second energizing member may be connected to the electrode. The thickness of the central portion of the second energizing member may be thinner than the thickness of the end portion. A breaking groove may be formed at the center of the second energizing member to serve as a starting point of the breaking when the pressure in the case exceeds a predetermined value. The fracture groove may be continuous or intermittently straight at the central portion of the second energizing member. The breaking groove may be a weak portion that becomes a starting point of breaking when the pressure in the case exceeds a predetermined value, or it may be locally formed at the center of the second energizing member.

The deformable member may be disposed between the first energizing member and the second energizing member. The end of the deformable member may be connected to the first energizing member and the central portion of the deformable member may be connected to the second energizing member. The central portion of the deformable member may be fixed to the second energizing member at a position surrounded by the broken groove. The deformable member may be non-conductive with the second energizing member when the pressure in the case exceeds a predetermined value. The deforming member may be deformed into a state in which the central portion protrudes toward the second energizing member when the second deforming member is in electrical continuity with the second energizing member, and the central portion protrudes toward the first energizing member when the second deforming member is not in contact with the second energizing member.

The first sealing member may be disposed between the first energizing member and the second energizing member. The first seal member may be insulating. The material of the first seal member may be, for example, resin or rubber. The first seal member may isolate the space surrounded by the first seal member, the first energizing member, and the second energizing member (the inner space of the current interruption device) from the external space of the current interruption device. That is, the first seal member may keep the internal space of the current interruption device airtight from the outside. The first sealing member may seal the first energizing member and the second energizing member on the outer side of the deforming member.

In the case, the second sealing member may be disposed between the inner wall of the case and the first energizing member. The second seal member may be disposed between the inner wall of the case and the enlarged diameter portion. The second seal member may keep the inside of the case hermetically from the outside of the case. The second seal member may be insulative. The material of the second seal member may be, for example, rubber. The material of the second seal member may be the same as or different from the material of the first seal member.

The airtightness of the current interruption device may be equal to or greater than the airtightness of the case. That is, the gas permeability (hereinafter referred to as the first gas permeability) between the first energizing member and the second energizing member sealed by the first sealing member is larger than the gas permeability of the case sealed by the second sealing member, (Hereinafter referred to as " second gas permeability "). In this case, a material having a gas permeability smaller than that of the material of the second sealing member may be used as the material of the first sealing member, and the materials of the first sealing member and the second sealing member are the same, It may be adjusted to be equal to or less than the gas permeability.

When the materials of the first seal member and the second seal member are the same, the width of the first seal member (the distance between the surface located on the inner side of the current interruption device and the surface located on the outer side) The distance between the surface located on the inner side and the surface located on the outer side). Alternatively, the contact area of the first seal member with the first energizing member and the second energizing member may be equal to or greater than the contact area of the second seal member with the case and the thickened portion. The airtightness of the current interruption device may be larger than the airtightness of the case.

The insulating member may be disposed between the first energizing member and the second energizing member. Further, the insulating member may be disposed between the deforming member and the first seal member. That is, the end of the deforming member may be fixed to the first energizing member on the inner side of the insulating member. The gap between the first energizing member and the second energizing member may be maintained by the insulating member. A gap may be formed between the first energizing member and the second energizing member outside the range where the insulating member is formed. The insulating member may have a ring shape. The insulating member may be disposed between the first energizing member and the second energizing member in a non-contact state with the deforming member and the first seal member. Further, the end of the first energizing member on the side of the second energizing member may be provided with a protrusion for receiving a part of the insulating member. More specifically, the surface of the first energizing member which is in contact with the end face of the insulating member on the side of the first energizing member among the end faces on the second energizing member side may be punched out from the surrounding surface not in contact with the insulating member. Likewise, the end face of the second energizing member on the first energizing member side may be provided with a protrusion for receiving a part of the insulating member. That is, the surface of the second energizing member which is in contact with the end face of the insulating member on the side of the second energizing member among the end face on the first energizing member side may be punched out from the surrounding surface not in contact with the insulating member.

The second deforming member may be disposed on the side opposite to the deforming member with respect to the second energizing member. Hereinafter, the deformable member disposed between the first energizing member and the second energizing member is referred to as a first deformable member, and the deformable member disposed on the opposite side to the first deformable member with respect to the second energizing member is referred to as a second deformable member . The second deformable member may be fixed to the second energizing member. The second deformable member may be formed between the second energizing member and the electrode assembly. The second deformable member may be separated from the inside and the outside of the current interruption device. That is, the second deformable member constitutes the outer surface of the current interruption device, and the pressure in the case may directly act on the second deformable member. Protrusions protruding toward the second energizing member may be formed at a central portion of the second deforming member on the second energizing member side. The projection may be opposed to a portion surrounded by the fracture groove of the second energizing member in a state away from the second energizing member. The projections may be of insulating property.

The second deformable member is in a state in which the central portion protrudes in a direction away from the second energizing member when the pressure in the case is equal to or less than a predetermined value and the central portion moves toward the second energizing member when the pressure in the case exceeds a predetermined value, The projection may contact the second energizing member. The protrusion may contact the second energizing member and may break the second energizing member so that the first deforming member and the second energizing member are not in contact with each other. The second deformable member may have the same structure as the first deformable member. The second deformable member may be made of a metal or a nonmetal.

As an example of the electrical storage device disclosed in this specification, a secondary battery, a capacitor, and the like can be given. As an example of an electrode assembly of a secondary battery, a laminate type electrode assembly in which a plurality of cells having opposing electrode bands (negative electrode and positive electrode) are laminated via a separator, a sheet-like cell having electrode bands opposed to each other through a separator A wound-type electrode assembly processed into a spiral shape can be given. Further, the power storage device disclosed in this specification can be mounted on a vehicle, for example, and can supply electric power to the motor. The structure of the electrical storage device will be described below. In the following description, a power storage device in which a current interruption device is connected to a negative terminal and a negative electrode will be described. The technique disclosed in this specification can also be applied to a power storage device in which the current breaking device is connected to the positive terminal and the positive electrode.

Example

(Embodiment 1)

The structure of the electrical storage device 100 will be described with reference to Fig. The power storage device 100 includes a case 18, an electrode assembly 52, a positive electrode terminal 2, a negative electrode terminal 30 and a current interrupting device 50. The case 18 is made of metal and has a substantially rectangular parallelepiped shape. The case 18 is provided with a lid portion 18a and a main body portion 18b. Inside the case 18, an electrode assembly 52 and a current cutoff device 50 are accommodated. The electrode assembly 52 includes a positive electrode and a negative electrode (not shown). The positive electrode tab 16 is fixed to the positive electrode, and the negative electrode tab 20 is fixed to the negative electrode. An electrolytic solution is injected into the case 18.

The positive electrode terminal 2 and the negative electrode terminal 30 communicate with the inside and outside of the case 18. The positive electrode terminal 2 and the negative electrode terminal 30 are arranged in one direction of the case 18. That is, both the positive electrode terminal 2 and the negative electrode terminal 30 are disposed in the same direction (on the side where the lid portion 18a is formed) with respect to the electrode assembly 52. [ The positive electrode terminal 2 is provided with a bolt portion 8. The bolt portion 8 is a portion of the positive electrode terminal 2 that is threaded to fasten the nut 10. The positive electrode terminal 2 is fixed to the case 18 by fastening the nut 10 to the bolt portion 8. One end of the positive electrode terminal 2 is located outside the case 18 and the other end is located inside the case 18. Similarly, the negative electrode terminal 30 is provided with a bolt portion 36. The bolt portion 36 is a portion of the negative electrode terminal 30 that is threaded to fasten the nut 38. The negative electrode terminal 30 is fixed to the case 18 by fastening the nut 38 to the bolt portion 36. One end of the negative electrode terminal 30 is located outside the case 18 and the other end is located inside the case 18.

A positive electrode lead (14) is connected to the positive electrode terminal (2). The positive electrode lead (14) is connected to the positive electrode tab (16). The positive electrode terminal 2 is electrically connected to the positive electrode tab 16 through the positive electrode lead 14. That is, the positive electrode terminal 2 is electrically connected to the positive electrode of the electrode assembly 52. The positive electrode lead 14 is insulated from the case 18 by the insulating sheet 12. The positive electrode terminal 2 and the nut 10 are insulated from the case 18 by an insulating member 58. [ An insulating seal member 56 is disposed between the positive electrode terminal 2 and the case 18 in the case 18. [ The seal member 56 is made of rubber. The clearance between the positive electrode terminal 2 and the case 18 is sealed by the sealing member 56. [ The bus bar 4 is fixed to the positive electrode terminal 2 by the bus bar bolt 6.

The current blocking device 50 is connected to the negative electrode terminal 30. Details of the current interruption device 50 will be described later. The current interrupting device 50 is connected to the negative electrode lead 24 through a metal connecting member 26. The negative electrode terminal 30 is electrically connected to the negative electrode tab 20 through the negative electrode lead 24. That is, the negative electrode terminal 30 is electrically connected to the negative electrode of the electrode assembly 52. The negative electrode lead 24 is insulated from the case 18 by the insulating sheet 22. The negative electrode terminal 30 and the nut 38 are insulated from the case 18 by the insulating member 28. [ An insulating second seal member 42 is disposed between the negative electrode terminal 30 and the case 18 in the case 18. [ The second seal member 42 is an insulating O-ring. The material of the second seal member 42 is rubber. The clearance between the negative electrode terminal 30 and the case 18 is sealed by the second seal member 42. [ The inside of the case 18 is kept airtight from the outside of the case 18 by the seal members 56 and 42. [ The bus bar 32 is fixed to the negative electrode terminal 30 by the bus bar bolt 34. [

In the electrical storage device 100, the negative electrode terminal 30 and the negative electrode tab 20 are electrically connected through the current interruption device 50 when the pressure in the case 18 is a predetermined value or less. That is, the negative electrode terminal 30 and the negative electrode are electrically connected. When the pressure in the case 18 exceeds a predetermined value, the current interrupting device 50 interrupts the conduction between the negative electrode terminal 30 and the negative electrode tab 20 to prevent current from flowing to the power storage device 100 .

Referring to Fig. 2, the current interruption device 50 will be described. The current interrupting device 50 includes a negative terminal 30, a metallic wave plate 88, and a first deformable member 80 made of metal. The negative electrode terminal 30 has a diameter-enlarged portion 37a and a protruding portion 37b. The enlarged diameter portion 37a is located in the case 18 and the protruding portion 37b protrudes to the outside of the case 18 through a through hole formed in the case 18. [ The protruding portion 37b is a portion of the negative electrode terminal 30 that protrudes upward from the case 18. A bolt portion 36 is formed in the projecting portion 37b. The bolt portion 36 is a portion of the projecting portion 37b where a screw is formed on the surface for fastening the nut 38. [ The negative electrode terminal 30 is an example of the first energizing member.

A part of the enlarged diameter portion 37a is opposed to the case 18. The second seal member 42 is disposed between the enlarged diameter portion 37a and the case 18. On the side of the wave plate 88 of the enlarged diameter portion 37a, a groove 92 and a dent 86 are formed. The indentation 86 is formed inside the groove 92. The end face 35 of the enlarged diameter portion 37a on the wave plate 88 side faces the wave plate 88 and is pushed toward the center. Concretely, the end face 35 is inclined as falling from the wave plate 88 as it goes from the end toward the center. The " groove " means a shape having a bottom surface surrounded by two side walls. The " dent " is simply a form having a height lower than the circumference, and a form having a step is also included in " dent. &Quot;

The wave plate 88 is disposed at a position facing the enlarged diameter portion 37a at a distance from the enlarged diameter portion 37a. The wave plate 88 is an example of the second energizing member. The first deformable member 80 and the enlarged diameter portion 37a are provided above the electrode assembly 52 between the electrode assembly 52 (see Fig. 1) and the case 18, Respectively. Grooves 96 are formed in the end face of the wave plate 88 on the side of the enlarged diameter portion 37a. The groove 96 is formed at a position facing the groove 92. A connecting member 26 is fixed to the wave plate 88. The wave plate 88 is electrically connected to the negative electrode tab 20 through the connecting member 26 and the negative electrode lead 24 (see also Fig. 1). The thickness of the central portion 88a of the wave plate 88 is thinner than the thickness of the end portion 88b. Further, on the opposite side of the enlarged diameter portion 37a, a fracture groove 90 is formed in the central portion 88a. The fracture groove 90 is continuous in the center portion 88a. A depression 89 is formed on the opposite side of the enlarged diameter portion 37a of the wave plate 88. The indentation 89 is formed at the end 88b of the wave plate 88. [

The first seal member 84 is disposed between the enlarged diameter portion 37a and the wave plate 88. The first seal member 84 is an insulating O-ring. The material of the first seal member 84 is rubber. The first seal member 84 insulates the large diameter portion 37a and the wave plate 88 and keeps the interior of the current interruption device 50 airtight. That is, the first seal member 84 seals the enlarged diameter portion 37a and the wave plate 88 to seal the space inside the current interruption device 50 into the space (The space in the main body 18). EPDM (ethylene propylene rubber), for example, can be used as the material of the seal member 56 (see Fig. 1), 42 and 84. In the electrical storage device 100, the gas permeability (first gas permeability) between the enlarged diameter portion 37a and the wave plate 88 is larger than the gas permeability between the case 18 and the enlarged diameter portion 37a Permeability). More specifically, the gas permeability of the first seal member 84 is adjusted to be equal to or less than the gas permeability of the second seal member 42. That is, the term " kept airtight " as used herein means that the airtightness is maintained to be equal to or less than a predetermined gas permeability.

An insulating member 94 is disposed between the enlarged diameter portion 37a (negative electrode terminal 30) and the wave plate 88. The insulating member 94 is disposed inside the first seal member 84. The insulating member 94 is ring-shaped. The insulating member 94 maintains a gap between the enlarged diameter portion 37a and the wave plate 88. The insulating member 94 prevents the enlarged diameter portion 37a and the wave plate 88 from contacting each other directly. Both ends of the insulating member 94 are located in the grooves 92, 96. Therefore, the insulating member 94 is restricted from moving toward the first deformable member 80 and the first sealing member 84. Even if the first seal member 84 is intended to move toward the first deformable member 80, the first seal member 84 contacts the insulating member 94 So that it does not move further inside.

The first deformable member 80 is disposed between the enlarged diameter portion 37a and the wave plate 88. The first deformable member 80 is a metallic diaphragm. The end portion 80b of the first deformable member 80 is fixed to the enlarged diameter portion 37a. More specifically, in a state in which the outer periphery of the first deformable member 80 abuts against the side wall of the protrusion 86 of the enlarged diameter portion 37a, (37a). The central portion 80a of the first deformable member 80 protrudes from the enlarged diameter portion 37a. In other words, the first deformable member 80 is closer to the wave plate 88 as it goes from the end portion 80b toward the central portion 80a. The central portion 80a of the first deformable member 80 is fixed to the wave plate 88 on the inner side of the fracture groove 90. [ More specifically, the central portion 80a is welded to the wave plate 88 in a range surrounded by the fracture groove 90. [

The support member 78 supports the enlarged diameter portion 37a of the negative electrode terminal 30 and the wave plate 88. The support member 78 includes a metal outer side portion 72, an insulating first inner side portion 74, and an insulating second inner side portion 75. The first inner side part 74 is disposed on the inner side of the outer side part 72 and above the second inner side part 75 (on the case 18 side). The second inner side portion 75 is disposed on the inner side of the outer side portion 72 and below the first inner side portion 74 (on the electrode assembly 52 side). The enlarged diameter portion 37a and the wave plate 88 are positioned by the outer side portion 72. Concretely, the wave plate 88 is fixed to the enlarged diameter portion 37a by fixing the outer side portion 72 after the first inner side portion 74 and the second inner side portion 75 are disposed at predetermined positions. The inner side portions 74 and 75 insulate the enlarged diameter portion 37a and the wave plate 88 from each other. By using the metal outer portion 72, the airtightness of the internal space of the current interruption device 50 can be further increased.

When the internal pressure of the case 18 is lower than a predetermined value, the negative terminal 30 is connected to the first deformable member 80, the breaking plate 88, the connecting member 26, the negative electrode lead 24, And the negative electrode. When the inner pressure of the case 18 is lower than a predetermined value, a gap is formed between the projection 95 and the wave plate 88.

For example, when the power storage device 100 becomes overcharged, the internal pressure of the case 18 rises and exceeds a predetermined value. When the internal pressure of the case 18 exceeds a predetermined value, a pressure difference is generated between the inside of the current blocking device 50 and the outside. As a result, the wave plate 88 is broken with the break groove 90 as a starting point. The first deformable member 80 and the wave plate 88 are separated from each other and the first deformable member 80 and the wave plate 88 are non-conductive. The negative electrode terminal 30 and the negative electrode are made nonconductive, so that it is possible to prevent a current from flowing between the positive electrode terminal 2 and the negative electrode terminal 30 (see FIG. 1). When the wave plate 88 is broken, the central portion 80a of the first deformable member 80 moves from the wave plate 88 side toward the enlarged diameter portion 37a. In other words, the first deformable member 80 is reversed. In addition, as described above, since the end surface 35 of the enlarged diameter portion 37a is recessed, the reversal of the first deformable member 80 does not interfere with the enlarged diameter portion 37a (negative electrode terminal 30). It is possible to prevent the first deformable member 80 and the wave plate 88 from being re-circulated after the wave plate 88 is broken. That is, it is possible to prevent the current from flowing again between the positive electrode terminal 2 and the negative electrode terminal 30 after the pressure in the case 18 rises and the current interruption device 50 operates.

Advantages of the electrical storage device 100 will be described. As described above, when the internal pressure of the case 18 rises due to overcharging or the like of the power storage device and exceeds a predetermined value, the current cutoff device 50 operates to turn off the negative electrode terminal 30 and the negative electrode. In the power storage device 100, gas may be generated in the case 18 due to, for example, decomposition of the electrolyte solution during the normal state, and the internal pressure of the case 18 may gradually rise. However, in the electrical storage device 100, the second seal member 42 is made of rubber and has gas permeability. Therefore, the gas generated in the normal state can pass through the inside of the second seal member 42 and move to the outside of the case 18. [ Therefore, the power storage device 100 can prevent the current blocking device 50 from operating due to the internal pressure of the case 18 exceeding the predetermined value in the normal state. The power storage device 100 operates only when the gas generated during the normal state moves to the outside of the case 18 and is in an overcharge state or the like.

Other advantages of the electrical storage device 100 will be described below. The airtightness of the internal space of the current interruption device 50 is enhanced by the outer side portion 72 of the support member 78 in addition to the first seal member 84 as described above. That is, the gas permeability between the enlarged diameter portion 37a and the wave plate 88 can be further reduced. Therefore, the gas generated in the case 18 can be prevented from moving from the outside of the current interruption device 50 to the inside. As described above, the current interruption device 50 operates by a pressure difference between the inside and the outside of the current interruption device 50. Therefore, if the gas permeability between the enlarged diameter portion 37a and the wave plate 88 is high, the current interruption device 50 can not operate normally. The power storage device (100) can further increase the sensitivity of the current cutoff device (50) by using the outside portion (72).

Both ends of the insulating member 94 are positioned in the grooves 92 and 96 so that the insulating member 94 is restricted from moving toward the first deformable member 80 and the first sealing member 84. [ It is possible to prevent the insulating member 94 from contacting the first deformable member 80 so as to narrow the movable range of the first deformable member 80 or deform the shape of the first deformable member 80. [ It is also possible to prevent the insulating member 94 from contacting the first seal member 84 and narrowing the space in which the first seal member 84 exists. If the space in which the first seal member 84 is present is narrowed, the filling rate of the first seal member 84 is increased, and the first seal member 84 may be damaged.

(Second Embodiment)

The power storage device 200 will be described with reference to Figs. 3 and 4. Fig. The power storage device 200 is a modification of the power storage device 100 and the structure of the current shutdown device 250 is different from the current cutoff device 50 of the power storage device 100. [ With respect to the power storage device 200, the same parts as the power storage device 100 are denoted by the same reference numerals as those of the power storage device 100, and the description thereof may be omitted.

The current interrupting device 250 is provided with the second deforming member 93 on the side opposite to the first deforming member 80 with respect to the wave plate 88. That is, the wave plate 88 is disposed between the first deformable member 80 and the second deformable member 93. The second deformable member 93 is a metal diaphragm. And the end 93b of the second deformable member 93 is fixed to the wave plate 88. [ More specifically, the end 93b of the second deformable member 93 is pressed against the side wall of the impeller 89 of the wave plate 88 by the outer peripheral edge of the second deformable member 93, (88).

Insulating protrusions 95 are formed on the side of the wave plate 88 of the second deformable member 93. The projection 95 is disposed at the central portion 93a of the second deformable member 93 and protrudes toward the wave plate 88. The projection 95 is opposed to the central portion 88a of the wave plate 88. More specifically, when the current interruption device 250 is viewed from the plane (the direction in which the projecting portion 37b is extended, that is, the direction from the axial direction of the negative electrode terminal 30) 90). The second deformable member 93 protrudes from the wave plate 88 as it moves away from the end 93b toward the central portion 93a.

In the current interrupter 250, the insulative second inner portion 275 extends to the lower side of the second deformable member 93. Thus, the second deformable member 93 and the electrode assembly 52 (see FIG. 3) are brought into contact with each other, thereby preventing the current cutoff device 250 from malfunctioning. The second inner side portion 275 is provided with a through hole 275a at the center thereof. Therefore, the central portion 93a of the second deformable member 93 is not covered with the second inner side portion 275. Therefore, it can not be prevented that the internal pressure of the case 18 is added to the second deformable member 93.

In the power storage device 200, when the internal pressure of the case 18 exceeds a predetermined value, the pressure in the case 18 (outside the current blocking device 250) is added to the second deforming member 93, The two deformable members 93 are deformed toward the wave plate 88. That is, the center portion 93a moves toward the central portion 88a of the wave plate 88. [ In other words, the second deformable member 93 is inverted about the end 93b. The projection 95 comes into contact with the wave plate 88 and the wave plate 88 breaks from the wave groove 90 as a starting point. The first deformable member 80 and the wave plate 88 are separated from each other so that the wave plate 88 and the first deformable member 80 are non-conductive.

Further, when the second deformable member 93 is reversed, a part of the projection 95 is located above the wave plate 88. In other words, the projection 95 passes through the central portion of the wave plate 88. The protrusion 95 restricts the first deformable member 80 from moving downward (toward the wave plate 88). Therefore, it is possible to more reliably prevent the first deformable member 80 and the wave plate 88 from being connected to each other again.

In the power storage device 200, the second deformable member 93 separates the inside of the current interrupter 250 from the outside. Therefore, a change in internal pressure of the case 18 directly acts on the second deformable member 93. [ The use of the second deformable member 93 which is reversed in accordance with the internal pressure of the case 18 makes it possible to surely break the wave plate 88 when the internal pressure of the case 18 exceeds a predetermined value. The use of the second deformable member 93 allows the wave plate 88 to be cut off from the outside of the current interruption device 250 (the inside of the case 18). It is possible to prevent the arc from coming into contact with the gas (for example, hydrogen) in the case 18 even if an arc occurs when the wave plate 88 breaks.

Further, in the above embodiment, a description has been given of a mode in which the current interruption device is connected to the negative electrode lead via the connecting member. However, the connecting member and the negative electrode lead may be integral parts. That is, the current shielding device may be directly connected to the member (negative electrode lead) connected to the negative electrode tab. When the current interrupting device is disposed between the positive electrode terminal and the positive electrode, the current interrupting device may be directly connected to the member (positive electrode lead) connected to the positive electrode tab.

The electrical storage device described above may be a structure in which a sealing member made of rubber is formed between the electrode terminal (first energizing member) and the case so that the gas in the case slowly moves out of the case. Therefore, a variety of materials can be used for the structure of the current interruption device and the components constituting the power storage device. Hereinafter, with respect to a lithium ion secondary battery, which is an example of a power storage device, the materials of the components constituting the power storage device are exemplified.

The electrode assembly will be described. The electrode assembly includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode has a positive electrode metal foil and a positive electrode active material layer formed on the positive electrode metal foil. The positive electrode tab corresponds to the positive electrode metal foil to which the positive electrode active material layer is not applied. The negative electrode has a negative electrode metal foil and a negative electrode active material layer formed on the negative electrode metal foil. The negative electrode tab corresponds to the negative electrode metal foil to which the negative electrode active material layer is not applied. The materials (active materials, binders, conductive additives, etc.) included in the active material layer are not particularly limited, and materials used for electrodes such as known power storage devices can be used.

As the positive electrode metal foil, aluminum (Al), nickel (Ni), titanium (Ti), stainless steel, or a composite material thereof can be used. Particularly, a composite material containing aluminum or aluminum is preferable. Further, as the material of the positive electrode lead, the same material as the positive electrode metal foil can be used.

The positive electrode active material may be a material capable of intruding and desorbing lithium ions, and Li ₂ MnO ₃ , Li (NiCoMn) _0.33 O ₂ , Li (NiMn) _0.5 O ₂ , LiMn ₂ O ₄ , LiMnO ₂ , LiNiO ₂ , LiCoO ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , Li ₂ MnO ₂ , and LiMn ₂ O ₄ . As the positive electrode active material, an alkali metal such as lithium, sodium, or sulfur may be used. These may be used alone, or two or more of them may be used in combination. The positive electrode active material is applied to the metal foil for positive electrode together with a conductive material, a binder and the like, if necessary.

As the negative electrode metal foil, aluminum, nickel, copper (Cu), or a composite material thereof can be used. Particularly, a composite material containing copper or copper is preferable. As the material of the negative electrode lead, the same material as the negative electrode metal foil can be used.

As the negative electrode active material, a material capable of intrusion and desorption of lithium ions is used. Carbon materials such as alkali metals such as lithium (Li) and sodium (Na), transition metal oxides including alkali metals, natural graphite, mesocarbon microbeads, highly oriented graphite, hard carbon and soft carbon, A silicon-containing alloy or a silicon-containing oxide may be used. It is particularly preferable that the negative electrode active material is a material that does not contain lithium (Li) in order to improve the battery capacity. The negative electrode active material is applied to the negative electrode metal foil together with a conductive material, a binder and the like as necessary.

The separator uses a porous material having insulating properties. As the separator, a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), or a woven or nonwoven fabric made of polypropylene, polyethylene terephthalate (PET), methylcellulose or the like can be used.

The electrolytic solution is preferably a nonaqueous electrolytic solution obtained by dissolving a supporting salt (electrolyte) in a nonaqueous solvent. As the nonaqueous solvent, a solvent containing a chain ester such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC) or ethyl methyl carbonate (EMC) Methyl propionate, or a mixture thereof may be used. As the supporting salt (electrolyte), for example, LiPF ₆ , LiBF ₄ , LiAsF ₆ or the like can be used.

Although specific examples of the present invention have been described above in detail, they are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples described above. In addition, the technical elements described in the present specification or drawings exert their technical usefulness solely or in various combinations, and are not limited to the combinations described in the claims at the time of filing the application. Further, the techniques exemplified in the present specification or drawings can achieve a plurality of objectives at the same time, and achieving one of them is technically useful.

Claims (4)

The case,
An electrode housed in the case,
An electrode terminal fixed to the case and adapted to exchange electricity with the electrode,
And a current interrupting device for interrupting a conduction between the electrode and the electrode terminal when the pressure in the case exceeds a predetermined value, the lithium ion secondary battery comprising:
The current cut-
A first energizing member fixed to the case and connected to the electrode terminal,
A second energizing member which is disposed at a position facing the first energizing member at an interval from the first energizing member and is connected to the electrode,
Wherein the first energizing member is disposed between the first energizing member and the second energizing member and has an end connected to the first energizing member and a central portion connected to the second energizing member, A deformation member which becomes non-conductive with the second energizing member when the value exceeds a predetermined value,
And a first sealing member which is disposed between the first energizing member and the second energizing member and keeps the interior of the current interrupting device hermetically from the outside of the current interrupting device,
A second sealing member for sealing the inside of the case from the outside of the case is disposed between the case and the first energizing member,
The gas permeability between the case sealed by the second sealing member and the first energizing member is lower than the gas permeability between the first energizing member sealed by the first sealing member and the second energizing member A lithium ion secondary battery having greater permeability. The method according to claim 1,
The current interrupting device is disposed on the side opposite to the deforming member with respect to the second energizing member and a protrusion protruding toward the second energizing member is formed on the second energizing member side, Further comprising a second deforming member which separates the inside and the outside of the current interrupting device,
And the material of the first seal member is rubber. delete The case,
An electrode housed in the case,
An electrode terminal fixed to the case and receiving electricity between the electrode and the electrode,
And a current interrupting device for interrupting a conduction between the electrode and the electrode terminal when the pressure in the case exceeds a predetermined value, the lithium ion secondary battery comprising:
The current cut-
A first energizing member fixed to the case and connected to the electrode terminal,
A second energizing member which is disposed at a position facing the first energizing member at an interval from the first energizing member and is connected to the electrode,
Wherein the first energizing member is disposed between the first energizing member and the second energizing member and has an end connected to the first energizing member and a central portion connected to the second energizing member, A deformation member which is non-conductive with the second energizing member when the value exceeds a predetermined value,
And a first sealing member which is disposed between the first energizing member and the second energizing member and keeps the interior of the current interrupting device hermetically from the outside of the current interrupting device,
A second sealing member for sealing the inside of the case from the outside of the case is disposed between the case and the first energizing member,
The gas permeability between the case sealed by the second sealing member and the first energizing member is lower than the gas permeability between the first energizing member sealed by the first sealing member and the second energizing member ≪ / RTI >
And the material of the second sealing member is rubber.

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